#include <stdio.h>

double f(double i){
    return i * i + 1.0 / i;
}
int main(){
    int m,n;
    double sum = 0.0;
    scanf("%d,%d",&m,&n);
    for(int i = m; i <= n; i++){
        sum += f(i);
    }
    printf("%.6lf",sum);
    return 0;
}
